Question

当从html选择处理“更改”事件时，我想获得最后选择的值/索引。

对于前。

$('#mySelect').live('change', function(event){
       var idx = $(this).prop('selectedIndex');
});

idx在更改事件触发器后保留值。我需要在事件触发之前选择的值。

Answer 1

如果你有多个选择，请尝试这样的事情：

var select = $('#mySelect');
select 
    .data("lastIndex", select[0].selectedIndex)
    .live('change', function(event){
        var idx = this.selectedIndex;
        var prevIdx = $(this).data("lastIndex");

        // Alert prev and new index
        alert(prevIds + " - " + idx);

        // Alert prev value and new value
        alert($(this).find("option").eq(prevIdx) + " - " + $(this).find("option").eq(idx));

        // Set new index as old index
        $(this).data("lastIndex", idx);
    });

Answer 2

我会将以前的值存储在不同的变量中并手动更新

// what is the value when <select> was just loaded?
var previous_value = $('#mySelect').prop('selectedIndex');

$('#mySelect').live('change', function(event){
       var idx = $(this).prop('selectedIndex');
       // at this point previous_value has the previous value and idx - current
       // ... do something here ...
       // updating previous_value for the next time
       previous_value = idx;
});

Answer 3

您可以使用事件处理函数之外的变量范围跟踪值，如下所示：

var mySelect = $('#mySelect'),
    previousValue = mySelect.val();

mySelect.live('change', function() {

    alert( mySelect.val() ); // alerts current value
    alert( previousValue ); // alerts previous value

    previousValue = mySelect.val(); // save so it can be referenced next time

});

Answer 4

你可以尝试这样的事情 -

var lastSeelctedlist = "";
$('#mySelect').live('change', function(event){
       lastSeelctedlist  = $(this).val();
// you rest of code
});

Answer 5

如果我找到你，那么这里是纯javascript的解决方案

function getLastSelected(e)
   {
    var s = e;
    var optionsSelected = [];
    for(var i =0;i<s.options.length;i++)
    {
     if(s.options[i].selected == true)
      {
        optionsSelected[optionsSelected.length] = {Value :  s.options[i].value,Text:s.options[i].text,Index : i};
      }
    }

    var lastSelected =((optionsSelected.length >0)?(optionsSelected[optionsSelected.length - 1]):(null)) ;
    return lastSelected; // or do what you have to do here 
//put it in custom attribute or what ever 
   }

此函数参数是select tag id，return对象包含3个属性价值，文字，索引

在onchange事件上调用它

onchange = "getLastSelected(this)"

问候

在更改事件中更改之前获取html选择的值

5 个答案: